Printed-wiring boards are generally produced by an etching process which comprises laminating a copper foil on an insulating base material, forming a resist pattern on the copper foil, and etching away portions of the copper foil not covered by the resist to form a conductor pattern.
However, this etching process is not desirable because of the loss of expensive copper foil. Furthermore, the process is complicated because a sophisticated resist pattern must be formed for each board.
A transfer process is desirable because there is no loss of copper foil, and printed-wiring boards can be mass produced by repeating the simple steps of metal-plating and transfer as long as the resist can resist metal-plating and transfer steps. However, it is difficult to repeatedly use ordinary resists for metal or alloy mainly because they interlock with, or adhere to, an adhesive or an uncured base material during the transfer step, and undergo delamination from the carrier or leave the adhesive or uncured base material on the resist.
Another serious problem with the transfer process is shown in FIG. 1. The metal skin 2 enters into uneven surface contact with the resist 3, leading to difficult delamination of the metal skin. Furthermore, upon delamination of the carrier from the base material after the transfer step, delamination takes place between the adhesive and the base material or within the uncured base material, leaving the metal skin on the carrier. This phenomenon can be considerably removed by giving the carrier some curvature. More specifically, the problem is partially eliminated by making the metal-plated surface convex. However, this does not sufficiently eliminate the problem.